F1technical.net

“With the LMP 900s, you had to be very careful when setting the rake of the cars. Typically you’d see ground clearance of 30mm at the front and 75-80 at the rear"

machin wrote:I can't find anything in the real LMP1 rules, but this interview (admittedly old, but still the right sort of car), suggests we may actually be a bit too LOW at the rear:

“With the LMP 900s, you had to be very careful when setting the rake of the cars. Typically you’d see ground clearance of 30mm at the front and 75-80 at the rear"

" if the rear was reduced – to reduce drag, say by fitting soft rear springs or reducing ride height – as we’ve seen, you could get into trouble."

machin wrote:Well he does go on to say:

" if the rear was reduced – to reduce drag, say by fitting soft rear springs or reducing ride height – as we’ve seen, you could get into trouble."

So it sounds like he's talking about dynamic heights.... Given that ....a 45mm front and rear seems like a good compromise...?

machin wrote:Well it seems like a good compromise to me: Option 1 should remain as it is and option 2 changed to be an "Option1+", where the competitor must model the duct...

..... But how do the other competitors feel as I think Option 2 was really added at the request of you guys...

CAEdevice wrote:You should include a legend: are you showing pressure or velocity? Wich scale range did you use? There is something strange with the diffuser, are you sure that the car is correctly oriented?

If the first picture is representing pressure, it is quite strange the high pressure inside the diff and under the rear wing.

CAEdevice wrote: ... but at that time we could not imagine the difficulties that Julien would have met. I could simulate the heat exchanger defining the poruos media in 20 minutes with KARALIT CFD (the same, I think, AaratzH with SWX Flow Sim and Mantium with OpenFoam) but to write a framework for Windows seems to be complicated. I think that Julien is making a too heavy job alone.

SR71 wrote: Now I just need to learn what this means

LVDH wrote:

SR71 wrote: Now I just need to learn what this means

That means that your challenge has started. You have a lot of work ahead of you.

Legends would help us a lot to understand better what is happening. The first one, I guess, shows the pressure distribution on you car's surface. Blue should indicate low pressure. So infront of your diffuser it should be dark blue and in the duffuser light blue. Why yours is red is a good question. The design does not look terribly wrong. Maybe the simulation did not converge. You should have a look at your residual and force curves plotted against the iterations. The residuals should somewhat smoothly go below a threshold like 1e-3. Your forces should smoothly and then flat converge towards some value. If it is fluctuating like crazy you have a problem.

The histogram plot shows the chunks of forces acting on your car, here in X-direction. You should get one for drag and one for down force. In this case I am not sure which you are showing as your red diffuser is a bit confusing. In any case you will see a nice, high tower around your rear wing as it should create a lot of down force but also drag.
Maybe you could create a new thread about your car. Last year we helped, I think RicME, a lot in his own thread on his car got much better and it is fun for everyone to help and know everything better.